abse/gameboy-advance

INDUCTOR_REPLACEMENT_REVIEW.txt

LOCAL INDUCTOR REPLACEMENT REVIEW — based on published v0.0.37

L_BAT_BUCKBOOST: replace Coilcraft XGL4020-152MEC / C7417180 with
APV APH0420T1R5M / C5349662. Live JLCPCB listing: 18,246 stocked;
small-quantity component price USD 0.0978 versus USD 5.9462 for Coilcraft.
Extended-component assembly charges and attrition are separate.

APV manufacturer datasheet, revised 2026-08-12:
1.5uH +/-20%; DCR max 46mOhm; Isat typical 5.50A, other tabulated
Isat value 4.57A; Irms typical 5.00A, other tabulated value 4.41A.
Typical Isat uses a 30% inductance drop; typical Irms uses a 40C rise.
Do not treat typical current figures as temperature-independent guarantees.
Body nominal 4.4x4.2x1.8mm, tolerance envelope 4.75x4.5x2.0mm.
Imported supplier OBJ is 4.4x4.2x2.1mm; clearance checked with the
larger 4.75x4.5x2.1mm envelope. Real supplier STEP/OBJ retained.

Use APV recommended land pattern, page 2: two 1.50x2.50mm pads,
2.20mm inner-edge gap, centres +/-1.85mm. Imported library pad geometry
was corrected to this manufacturer drawing. Nonpolar device rotated180deg
to retain left/right logical port correspondence. Centre shifted0.30mm left.
Two switching branches remain top-layer, 0.40mm wide, below5.5mm.
Power-save control uses two0.30/0.45mm full-through vias and a bottom route.
VIN-to-mode branch adjusted around the larger pad. USB routes unchanged.
No DRC, spacing, length or power-width limits relaxed.

TI TPS63070 datasheet section9.2.2.2 requires actual load-based saturation
selection with20% peak-current margin. Conservative example:
VIN3.2V, VOUT5.1V, efficiency85%, L1.2uH, f2.1MHz, output1.5A gives
3.049A peak; adding20% gives3.659A, below4.57A tabulated value.
At2A output the same20% margin is4.784A, exceeding4.57A: this replacement
is not qualified here for continuous2A worst-case boost operation.
The1.5A calculation is an assumption, not a measured board load or enforced
current limit. Prototype must verify maximum-load current, startup behavior,
voltage stability and temperature at low batteries, high brightness and audio.
Higher DCR increases copper losses compared with the Coilcraft part.

Local native build, all original mapped net partitions, USB ground-reference,
button contact, schematic and PCB style checks pass. Existing23 requested-width
warnings retained. All22 enclosure envelope checks pass.
Included in revision0.0.39; see ELECTRICAL_PROTOTYPE_REVIEW.txt for current qualification.